Feature/frontmatter yaml parser

ansi/codeblock.go

@@ -118,8 +118,12 @@ func (e *CodeBlockElement) Render(w io.Writer, ctx RenderContext) error {
 		mutex.Unlock()
 	}
 
+	ic := " "
+	if rules.IndentToken != nil {
+		ic = *rules.IndentToken
+	}
 	iw := indent.NewWriterPipe(w, indentation+margin, func(wr io.Writer) {
-		renderText(w, ctx.options.ColorProfile, bs.Current().Style.StylePrimitive, " ")
+		renderText(w, ctx.options.ColorProfile, bs.Current().Style.StylePrimitive, ic)
 	})
 
 	if len(theme) > 0 {

ansi/elements.go

@@ -34,8 +34,6 @@ type Element struct {
 // NewElement returns the appropriate render Element for a given node.
 func (tr *ANSIRenderer) NewElement(node ast.Node, source []byte) Element {
 	ctx := tr.context
-	// fmt.Print(strings.Repeat("  ", ctx.blockStack.Len()), node.Type(), node.Kind())
-	// defer fmt.Println()
 
 	switch node.Kind() {
 	// Document

ansi/renderer.go

@@ -1,6 +1,7 @@
 package ansi
 
 import (
+	localast "github.com/charmbracelet/glamour/extension/ast"
 	"io"
 	"net/url"
 	"strings"
@@ -37,6 +38,7 @@ func NewRenderer(options Options) *ANSIRenderer {
 // RegisterFuncs implements NodeRenderer.RegisterFuncs.
 func (r *ANSIRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
 	// blocks
+	reg.Register(localast.KindFrontmatter, r.handleFrontmatter)
 	reg.Register(ast.KindDocument, r.renderNode)
 	reg.Register(ast.KindHeading, r.renderNode)
 	reg.Register(ast.KindBlockquote, r.renderNode)
@@ -86,6 +88,10 @@ func (r *ANSIRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
 	reg.Register(east.KindEmoji, r.renderNode)
 }
 
+func (r *ANSIRenderer) handleFrontmatter(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	return ast.WalkContinue, nil
+}
+
 func (r *ANSIRenderer) renderNode(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
 	// _, _ = w.Write([]byte(node.Type.String()))
 	writeTo := io.Writer(w)

extension/_test/frontmatter.txt

@@ -0,0 +1,18 @@
+1
+//- - - - - - - - -//
+---
+title: A Title
+longText: |
+   Long text spanning multiple
+   lines of input
+number: 120
+---
+//- - - - - - - - -//
+<!--
+longText: Long text spanning multiple
+lines of input
+
+number: 120
+title: A Title
+-->
+//= = = = = = = = = = = = = = = = = = = = = = = =//

extension/ast/frontmatter.go

@@ -0,0 +1,29 @@
+package ast
+
+import (
+	"fmt"
+	"github.com/yuin/goldmark/ast"
+)
+
+// Frontmatter AST Node holding parsed YAML Frontmatter.
+// Status Parse Error or empty.
+type Frontmatter struct {
+	ast.BaseBlock
+	MetaData map[interface{}]interface{}
+	Status   string
+}
+
+var KindFrontmatter = ast.NewNodeKind("Frontmatter")
+
+func (f Frontmatter) Kind() ast.NodeKind {
+	return KindFrontmatter
+}
+
+func (f *Frontmatter) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["_status"] = fmt.Sprintf("%v", f.Status)
+	for key, value := range f.MetaData {
+		m[fmt.Sprintf("%v", key)] = fmt.Sprintf("%v", value)
+	}
+	ast.DumpHelper(f, source, level, m, nil)
+}

extension/frontmatter.go

@@ -0,0 +1,138 @@
+package extension
+
+import (
+	"bytes"
+	"fmt"
+	localast "github.com/charmbracelet/glamour/extension/ast"
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+	"gopkg.in/yaml.v3"
+	"regexp"
+	"sort"
+	"strings"
+)
+
+type FrontmatterResultConsumer interface {
+	HandleFrontmatter(frontmatter map[string]interface{})
+}
+
+type frontMatterParser struct {
+	Handler FrontmatterResultConsumer
+}
+
+func (f frontMatterParser) Trigger() []byte {
+	return []byte("---")
+}
+
+func (f frontMatterParser) Open(parent gast.Node, reader text.Reader, pc parser.Context) (gast.Node, parser.State) {
+	line, _ := reader.PeekLine()
+	line = bytes.TrimRight(line, "\r\n")
+	if matched, _ := regexp.Match("^-{3,}$", line); matched {
+		reader.AdvanceLine()
+
+		// read all lines and interpret as yaml
+		var buf bytes.Buffer
+		var y map[interface{}]interface{}
+		for {
+			line, _ = reader.PeekLine()
+			if matched, _ := regexp.Match("^-{3,}$", []byte(strings.TrimRight(string(line), "\r\n"))); !matched {
+
+				buf.Write(line)
+			} else {
+				break
+			}
+			reader.AdvanceLine()
+		}
+		if err := yaml.Unmarshal(buf.Bytes(), &y); err != nil {
+			fmt.Errorf("unable to parse Frontmatter as YAML %s", err.Error())
+			return &localast.Frontmatter{MetaData: nil, Status: err.Error()}, parser.NoChildren
+		}
+		result := localast.Frontmatter{MetaData: y}
+		if f.Handler != nil {
+			var m = make(map[string]interface{})
+			for key, value := range y {
+				m[fmt.Sprintf("%v", key)] = value
+			}
+			f.Handler.HandleFrontmatter(m)
+		}
+		return &result, parser.NoChildren
+	}
+	return nil, parser.NoChildren
+}
+
+func (f frontMatterParser) Continue(node gast.Node, reader text.Reader, pc parser.Context) parser.State {
+	// all parsing done in Open already
+	return parser.Close
+}
+
+func (f frontMatterParser) Close(node gast.Node, reader text.Reader, pc parser.Context) {
+	// nothing to do
+}
+
+func (f frontMatterParser) CanInterruptParagraph() bool {
+	return false
+}
+
+func (f frontMatterParser) CanAcceptIndentedLine() bool {
+	return false
+}
+
+var DefaultFrontMatterParser = &frontMatterParser{}
+
+func NewFrontMatterParser() parser.BlockParser {
+	return DefaultFrontMatterParser
+}
+
+type FrontmatterHTMLRenderer struct {
+	Config html.Config
+}
+
+// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
+func (r *FrontmatterHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(localast.KindFrontmatter, r.renderFrontmatterStart)
+}
+
+func (r *FrontmatterHTMLRenderer) renderFrontmatterStart(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		w.WriteString("<!--\n")
+		if node, ok := n.(*localast.Frontmatter); ok {
+			if node.Status != "" || node.MetaData == nil {
+				w.WriteString(node.Status)
+			} else {
+				keys := make([]string, 0, len(node.MetaData))
+				for key := range node.MetaData {
+					keys = append(keys, fmt.Sprintf("%v", key))
+				}
+				sort.Strings(keys)
+				for _, key := range keys {
+					w.WriteString(fmt.Sprintf("%s: %v\n", key, node.MetaData[key]))
+				}
+			}
+		}
+	} else {
+		w.WriteString("-->\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+func NewFrontmatterHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
+	r := &FrontmatterHTMLRenderer{
+		Config: html.NewConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetHTMLOption(&r.Config)
+	}
+	return r
+}
+
+func (f frontMatterParser) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(
+		parser.WithBlockParsers(
+			util.Prioritized(NewFrontMatterParser(), 99)))
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(util.Prioritized(NewFrontmatterHTMLRenderer(), 99)))
+}

extension/frontmatter_test.go

@@ -0,0 +1,20 @@
+package extension
+
+import (
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/testutil"
+	"testing"
+)
+
+func TestFrontMatterParsing(t *testing.T) {
+	markdown := goldmark.New(
+		goldmark.WithRendererOptions(
+			html.WithUnsafe(),
+		),
+		goldmark.WithExtensions(
+			DefaultFrontMatterParser,
+		),
+	)
+	testutil.DoTestCaseFile(markdown, "_test/frontmatter.txt", t, testutil.ParseCliCaseArg()...)
+}

glamour.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"os"
 
+	ext "github.com/charmbracelet/glamour/extension"
 	"github.com/muesli/termenv"
 	"github.com/yuin/goldmark"
 	emoji "github.com/yuin/goldmark-emoji"
@@ -39,10 +40,11 @@ type TermRendererOption func(*TermRenderer) error
 // TermRenderer can be used to render markdown content, posing a depth of
 // customization and styles to fit your needs.
 type TermRenderer struct {
-	md          goldmark.Markdown
-	ansiOptions ansi.Options
-	buf         bytes.Buffer
-	renderBuf   bytes.Buffer
+	md                 goldmark.Markdown
+	ansiOptions        ansi.Options
+	buf                bytes.Buffer
+	renderBuf          bytes.Buffer
+	frontMatterHandler ext.FrontmatterResultConsumer
 }
 
 // Render initializes a new TermRenderer and renders a markdown with a specific
@@ -71,13 +73,20 @@ func RenderBytes(in []byte, stylePath string) ([]byte, error) {
 	return r.RenderBytes(in)
 }
 
+func (tr *TermRenderer) HandleFrontmatter(frontmatter map[string]interface{}) {
+	if tr.frontMatterHandler != nil {
+		tr.frontMatterHandler.HandleFrontmatter(frontmatter)
+	}
+}
+
 // NewTermRenderer returns a new TermRenderer the given options.
 func NewTermRenderer(options ...TermRendererOption) (*TermRenderer, error) {
 	tr := &TermRenderer{
 		md: goldmark.New(
 			goldmark.WithExtensions(
 				extension.GFM,
 				extension.DefinitionList,
+				ext.DefaultFrontMatterParser,
 			),
 			goldmark.WithParserOptions(
 				parser.WithAutoHeadingID(),
@@ -88,6 +97,8 @@ func NewTermRenderer(options ...TermRendererOption) (*TermRenderer, error) {
 			ColorProfile: termenv.TrueColor,
 		},
 	}
+	// register Termrenderer as Callback for Frontmatter
+	ext.DefaultFrontMatterParser.Handler = tr
 	for _, o := range options {
 		if err := o(tr); err != nil {
 			return nil, err
@@ -112,6 +123,20 @@ func WithBaseURL(baseURL string) TermRendererOption {
 	}
 }
 
+func WithFrontMatterRenderer(r renderer.Renderer) TermRendererOption {
+	return func(termRenderer *TermRenderer) error {
+		termRenderer.md.Renderer().AddOptions(renderer.WithNodeRenderers(util.Prioritized(r, 99)))
+		return nil
+	}
+}
+
+func WithFrontMatterHandler(consumer ext.FrontmatterResultConsumer) TermRendererOption {
+	return func(termRenderer *TermRenderer) error {
+		termRenderer.frontMatterHandler = consumer
+		return nil
+	}
+}
+
 // WithColorProfile sets the TermRenderer's color profile
 // (TrueColor / ANSI256 / ANSI).
 func WithColorProfile(profile termenv.Profile) TermRendererOption {

go.mod

@@ -10,6 +10,7 @@ require (
 	github.com/olekukonko/tablewriter v0.0.5
 	github.com/yuin/goldmark v1.7.4
 	github.com/yuin/goldmark-emoji v1.0.3
+  gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c
 )
 
 require (

go.sum

@@ -44,3 +44,6 @@ golang.org/x/net v0.27.0/go.mod h1:dDi0PyhWNoiUOrAS8uXv/vnScO4wnHQO4mj9fn/RytE=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.22.0 h1:RI27ohtqKCnwULzJLqkv897zojh5/DwS/ENaMzUOaWI=
 golang.org/x/sys v0.22.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=